The present invention pertains generally to chemical process technology and more particularly to a fluid baffle, said baffle being positionable beneath a sprayer and/or within an existing fluid connecting tank or sump so as to facilitate continuous and complete mixing and/or recirculation of a liquid chemical, solution or suspension held therein.
The fluid baffle of the present invention is particularly useful in chemical process machines used in the manufacture of printed circuit boards and will be described herein with particular reference thereto. It will be appreciated, however, that the fluid baffle of the present invention may be useable in connection with many types of chemical process machines in addition to those employed in circuit board manufacturing applications.
It is common practice in the field of electronic circuit board manufacturing to employ conveyorized, spray process machines wherein one or more liquid chemicals, suspension or solutions are spray applied to circuit boards as they pass along a fixed conveyor path. Considerations of economy normally require that the liquid chemical, suspension or solution be recirculated and reused numerous times until such liquid chemical, solution or suspension has become chemically exhausted, contaminated or otherwise no longer useable. Typical spray process machines used in such applications generally comprise one or more mechanical conveyors having sprayer heads or nozzles positioned above and/or below the conveyor so as to spray apply the desired chemical solutions and/or suspensions to the circuit boards as they move along the conveyor path. A sump or catch tank is positioned below the conveyor to catch the runoff liquid chemical, solution and/or suspension after it has been spray applied to the passing circuit boards. This solution and/or suspension is accumulated within the sump or catch tank and is then taken up by one or more pumps, recirculated to the spray heads/spray nozzles wherefrom it is resprayed upon the conveyor path.
The use of standard spray processing machinery with certain suspensions or slurries is problematic. For example, when unstable suspensions (e.g. a slurry of pumice particles within a liquid matrix) are employed, it is generally desirable to maintain such suspensions under substantially continuous motion to prevent settling and separation of particulate matter. Many sumps are, however, not properly designed to permit the continuous motion to hold the material in suspension. In most spray process machines the sumps used in recirculating the liquid chemical, suspensions or solutions incorporate sharp corners or "dead zones" wherein the suspension may settle out and cake. Such settling out and caking is undesirable in that it results in a diminution in the concentration of solid particulate matter contained in the recirculating suspension/slurry and, further, because it complicates emptying and cleaning the sump interior.
The use of certain liquid chemicals or solutions in standard collection sumps may also be problematic. For instance, solutions which tend to form precipitates or chemicals which require substantial oxygenation may tend to form such precipitate or become oxygen depleted if allowed to stand within sharp corners or dead zones without periodic recirculation, turnover and/or aeration. Such precipitate formation or oxygen depletion may result in diminished reactivity of the solution or processing problems to the clogging of certain machine components with solid precipitant matter.
Thus, there remains a need in the art for an improved sump or tank configuration which will permit efficient, complete recirculation and mixing of liquids, suspensions or solutions without permitting such liquids to stand idle or become trapped within grooves, corners or other specific areas of the sump.